In recent years, the presence or absence of a mutation in a particular gene has been emphasized in various fields. For example, in DNA testing in forensic medicine, confirmation of the presence and absence of single nucleotide substitution by mutation or polymorphism in DNA has already been well known as a method for individual identification. Also, in the field of medicine, correlation between specific genetic polymorphism and drug sensitivity has been known, and trials to reduce the risk of drug-induced health disaster have been carried out by investigating specific genetic polymorphism. In addition, the detection of mutation in the gene is also employed for detection of a mutant-type DNA holder of hereditary disease, and is gaining importance than before.
And, as a method for detecting gene mutation, a loop hybrid method (LH method) in which single-stranded oligo DNA is added to the reaction solution after the PCR reaction of DNA fragment and hybridized with objective DNA fragment, and the obtained hybrid is separated by electrophoresis based on the structural differences, and discriminate the separated mutant gene by reacting with intercalator as needed, has been known (Patent Literature 1, Non-patent Literature 1).